1. Field of the Invention
This invention relates to a tape tensioning device for a tape recorder which operates, when a tape cassette in which a tape is slack is loaded, to automatically eliminate any slack in the tape to permit subsequent starting of a reproducing action.
2. Description of the Related Art
When a tape cassette is left unused for a considerable time interval, the magnetic tape within the cassette may unreel into a slacking fractional condition due to vibrations of the cassette from the outside and so forth. If a cassette tape in such condition is loaded into a tape recorder and used, then there is the possibility that on starting the slack tape may wind itself around a capstan or a pinch roller and the tape or the tape recorder may be damaged thereby.
Even from the fact that a large number of patent applications have been made so far as a countermeasure for the problem, it can be understood how seriously people having ordinary skill in the art have tackled the problem. However, the prior art devices either try to improve a mechanism around a pinch roller or a capstan so as to prevent a slack tape from entering between the pinch roller and the capstan or try to detect it without a moment's delay that a tape has wound itself around a pinch roller or a capstan.
The former has a drawback that it cannot prevent a tape from entering between a pinch roller and a capstan with certainty, while the latter only notifies the fact that a tape has wound itself around a pinch roller of a capstan and does not produce a fundamental countermeasure. Further, since neither of them tensions a tape, it is cumbersome that, when there is tape slack or when a tape winds itself around a pinch roller or a capstan, the tape recorder must be stopped by hand promptly to cope with the situation.
Furthermore, Japanese Utility Model Publication No. 1-27135 discloses the concept that when a tape slack eliminating action is made, only braking of the tape take-up side is released while the reel spindle of the tape supply side remains braked.
However, with this prior art device, an additional operating action called "tape slack eliminating action" is needed to tension the slack tape, which is laborious and time-consuming.